Government meteorologists on Thursday revised their outlook for the ongoing 2023 Atlantic hurricane season, now calling for a 60% chance of above-normal activity through Nov. 30, up from 30% originally forecast in May, shortly before the season started.

The likelihood of near-normal activity decreased to 25% from 40%, while the chances of below-normal activity shrank to 15% from 30%, according to the National Oceanic and Atmospheric Administration. The agency said it is 70% confident in its updated projections.

NOAA’s forecasts call for 14 to 21 named storms, defined as having winds of 39 mph or greater. Of those, six to 11 could become hurricanes with winds of 74 mph or greater.  Of those, two to five could morph into major hurricanes with winds of 111 mph or greater. The updated figures include four named storms that have already moved through. Of those, one, Hurricane Don, achieved hurricane status in late July, if only for a day.

An average Atlantic hurricane season produces 14 named storms, though there have been years such as 2021 when it was as high as 30. Of the 14 storms on average, seven become hurricanes and three become major hurricanes. This is the fifth time in the forecast’s 20-year history that it has revised its forecasts upward to this extent.

Record warm Atlantic ocean surface temperatures are the primary factor in NOAA’s revised forecast, said Matthew Rosencrans, lead hurricane season forecaster with NOAA’s Climate Prediction Center. Rosencrans said he analyzed ocean surface temperatures as far back as 1950.

The record temperatures have neutralized the effect of a weather phenomenon known as El Nino, which usually results in atmospheric conditions that help to lessen tropical activity during the Atlantic hurricane season, NOAA said. So far, those limiting conditions have been slow to develop and may not be fully in place for the balance of the current season, NOAA said.

“Considering these factors, the updated outlook calls for more activity, so we urge everyone to prepare now for the continuing season,” Rosencrans said.